1. Field of the Invention
This invention generally relates to a copying apparatus, and, in particular, to a split scanning copying apparatus in which an original holding surface is split into two sections thereby allowing to reproduce original images in the split two sections on separate two copy surfaces, respectively. More specifically, the present invention relates to an electrophotographic copying apparatus having multiple modes of operation one of which is a split scanning mode in which two original images placed on an original holding surface are reproduced on two separate copy surfaces, such as front and rear surfaces of a copy sheet or two separate copy sheets.
2. Description of the Prior Art
A prior art copying apparatus for making two copies from two original images located at an original holding surface will first be described with reference to FIG. 1a. In such a prior art copying apparatus, an original document 2 is placed on a contact glass, which serves as an original holder, and a light source 3 is located below the contact glass 1. During a copying operation, with the surface of the original document 2 being divided into a first original surface section X and a second original surface section Y, the light source 3 is first caused to scan from a first reference position (home position) indicated by the solid line to a second reference position indicated by the one-dotted line in the direction indicated by the arrow S thereby illuminating the first original surface section X, and, then, the light source 3 is caused to move in the same direction from the second reference position to a terminal end position indicated by the two-dotted line thereby illuminating the second original surface section Y, whereby the original images at the respective first and second original surface sections X and Y are reproduced on separate copy surfaces. In this case, a boundary position Q between the first and second original surface sections X and Y varies depending on the length Z of the original document 2 so that the second reference position, where the light source 3 initiates its illumination of the second original surface section Y, varies according to the size of length Z. For this reason, according to the prior art, there is provided a detector (not shown) for detecting the boundary position Q, and this detector is manually moved to the boundary position Q for each original document 2 placed on the contact glass 1 so that the boundary position Q or second reference position for the light source 3 is set for a particular original document 2 from which copies are to be made. However, it is not only cumbersome to set the detector at a right position by moving it manually for each original document, but also difficult to establish the second reference position by moving the detector to be properly located at the boundary position Q.
Such a prior art copying apparatus can also be used in other modes of copying operation than the split scanning mode as described above. For example, it can be used to make a copy from one page of a book type original or from a half of a sheet type original. In such a case, an original is required to be placed on the contact glass 1 in an awkward fashion depending on the position of an original image to be copied. For example, as shown in FIG. 1b, in the case where the right-hand page of a book type original located to the right of a vertical reference plate 85 for determining the position of an original is to be copied, the original 2 must be placed on the contact glass 1 either covering the reference plate 85 as shown in FIG. 1b or being rotated with its top at bottom. In the former case, since the original 2 partly sticks out of the contact glass 1, the apparatus itself must be made larger in size and attention must be paid so as not to impair the projecting portion of the original. In the latter case, it is cumbersome to manually rotate the original top-side bottom so as to set it in position, and, moreover, when making copies of successive pages, since the book original must be rotated top-side bottom each time after making one copy, there is a chance that one or more pages are copied without rotating the book original appropriately, in which case it will be more cumbersome because all of the copies must be checked one by one as to their orientation.